All posts tagged early melt

Greenland — a region vulnerable to the slings and arrows of human-forced climate change — appears set to experience both considerable warming and a significant melt spike this week.

Starting on Wednesday, May 3, a sprawling dome of high pressure is expected to begin to extend westward from the far North Atlantic and out over Iceland. As the high pressure dome builds to 1040 mb over the next couple of days, its clockwise flow will thrust abnormally warm and moist air northward out of the Atlantic. This air-mass is expected first to over-ride eastern Greenland, then run up into Baffin Bay, finally encompassing most of the island and its vast, receding glaciers.

(May 5, 2017 GFS model run as shown by Earth Nullschool is predicted to produce widespread above-freezing temperatures over the surface of the Greenland Ice Sheet. Such warming is expected to be accompanied by rainfall over a number of glaciers. Image source: Earth Nullschool.)

For those of us living in more southerly climes, a temperature of 6 C (43 F) may not sound very warm. But for the northeastern region of Greenland shared by the Zachariae, Brittania, Freja, and Violin Glaciers, such temperatures far exceed ordinary expectations for early May. They are anything but normal. In fact, the building influx of heat is more reminiscent to readings Greenland would have tended to experience during summer — if at all — under past climate averages.

Unfortunately, the new climate presented by human-forced warming is now capable of producing some rather extraordinary temperature extremes. And the anomaly ranges that are predicted for the coming week are nothing short of outlandish.

According to climate reanalysis data, by May 5th, temperatures over northern and eastern Greenland are expected to range between 15 C above average over a wide region and between 20 and 28 C above average in the northeast. For the Fahrenheit-minded, that’s 27 to 50 degrees F above normal. Or the equivalent of a 102 F to 125 F May day high in Gaithersburg, MD.

(An amazing temperature spike is expected to ride up and over Greenland on May 3 to May 5. This warming is expected to produce very extreme above average temperatures for this time of year. Image source: Global and Regional Climate Anomalies.)

Overall excessions for Greenland temperature are also predicted to be quite extraordinary for the day — hitting nearly 9 degrees Celsius (16 F) above average for the whole of this large island. So much warmth extending so far inland and combining with liquid precipitation, if it emerges as predicted in these GFS climate models, is likely to produce a significant early season melt spike — especially over southern and eastern Greenland. In places, these temperatures exceed expected normal summer conditions for Greenland’s glaciers. So it is difficult to imagine a situation where a significant surface melt spike does not occur if these predicted temperatures emerge.

The warming trend that we provided predictive analysis for yesterday has barely even begun and we already have visible dark, open water off Point Barrow, Alaska as of late Tuesday evening on April 29. A large polynya that had opened up off the northern Alaskan coast has now extended well past Barrow and landward toward the near-shore waters. By late evening, the open water had invaded to within about 200 yards of shore along and past the Point Barrow coastline.

In broader summary, the open water polynya stretches from Cape Lisburne to past Point Barrow and measures between 20 and 50 miles in width. General trends show this large polynya continuing to expand northward into the Chukchi Sea, a motion that is likely to continue for at least the next few days.

Some cooling will likely return after the currently building Arctic heatwave, but it is questionable if it will be enough to result in a refreeze given the prevailing and much warmer than usual conditions.

Sea ice break-up at Point Barrow typically begins in mid-to-late June. It often involves both the formation of open water offshore as well as sea ice motion near-shore. Though the polynya removed ice from the off-shore waters of Point Barrow today, the near-shore ice still remains grounded, so this admittedly impressive event cannot technically be considered a break-up. That said, it appears that we are seeing a very early initiation of melt conditions for the Barrow region.

With warmer weather settling in, heat stresses to the local and regional sea ice will likely continue to ramp up. So, in other words, this early season melt event has only just begun.

(Large polynya extending from Cape Lisburne to about 80 miles past Point Barrow on April 28. The polynya continued to enlarge even as it invaded the near-shore regions of Point Barrow on April 29th. Image source: LANCE-MODIS.)

Over the past week, large melt ponds emerged off the coast of Barrow Alaska. These ponds formed after successive days of ‘warm’ weather with highs ranging between 40 and 65 degrees Fahrenheit. Constant sunlight and above-freezing temperatures in this region have also contributed to the formation of numerous smaller melt ponds and large holes in the sea ice.

Break-up of sea ice off Barrow usually occurs in early to mid July and is characterized by off-shore ice moving parallel to the coast. On the films provided by the Barrow Ice Cam site, sporadic ice motion was visible during a number of days over the past week. So it appears that ice break-up is currently ongoing, if not quite complete. If confirmed, the break-up at Barrow for this year will be a few weeks ahead of schedule.

Between February and March of this winter, powerful off-shore winds drove ice away from the coast even as it created an upwelling of warm water currents from beneath. The result was a rare appearance of open water during winter. But freezing temperatures and an abating of the winds caused the sea ice to rapidly return and re-freeze.

The current melt is well under-way and will be far more permanent than the brief opening of water that appeared in March. The ice near Barrow has suffered a long pummeling from sunlight and above-freezing temperatures. Now it appears ready to relinquish its grip on this frozen city, if only for a brief time.